2018 ASHS Annual Conference

Abelia is a genus of flowering woody shrubs with high ornamental and landscape potential. Among the cultivars commercially available A. ‘Raspberry Profusion’, a hybrid between A. ‘Edward Goucher’ x A. chinensis, stands out for its superior ornamental characteristics of rapid growth, drought tolerance, dark green glossy leaves, long flowering period, unique pink-red flowers, and pink sepals that remain in the plant during fall. Even though A. ‘Raspberry Profusion’ roots successfully from shoot cuttings, the propagation rate is limiting commercial production. A more efficient and faster protocol is needed. In this study we report the development of an in vitro micropropagation protocol.

One node microcuttings from greenhouse-grown plants of two genotypes, A. ‘Francis Mason’ (as a control) (FM) and A. ‘Raspberry Profusion’ (RP), were cultured on Murashige and Skoog (MS) medium with vitamins or Woody Plant Medium (WPM) with vitamins both supplemented with 30 g∙L^-1 sucrose, 8 g∙L^-1 agar, pH adjusted to 5.9 and either 1 or 2 mg∙L^-1 of 6-Benzylaminopurine (BA). Genotype and type of media had a significant effect on the number of shoots and nodes/shoot obtained in vitro after 4 weeks. FM produced more shoots on WPM (1.6 shoots and 3.2 nodes/shoot) than MS (1 shoot and 1.5 nodes/shoot), but no significant differences were observed between RP on WPM (0.7 shoots and 1.2 nodes/shoot) and RP on MS (0.9 shoots and 1.2 nodes/shoot).

The effect of the origin of the explant was tested on RP. One node microcuttings from greenhouse or field-grown plants were cultured on WPM supplemented with 30 g∙L^-1 sucrose, 8 g∙L^-1 agar, pH adjusted to 5.9 and either 1 or 2 mg∙L^-1 of BA. After 4 weeks of culture, BA had no significant difference in the number of shoots and nodes/shoot obtained in vitro; however, the field-grown explants performed significantly better (1.2 shoots and 2.2 nodes/shoot) than the greenhouse explants (0.2 shoots and 0.2 nodes/shoot).

The effect of type of cytokinin was also tested using 1 mg∙L^-1 of Thidiazuron (TDZ) or Kinetin (Kn) on FM and RP cultured on WPM. Type of cytokinin and genotype had significant effects on the number of shoots produced in vitro after 4 weeks. Best overall treatment was RP with TDZ producing an average of 3 shoots, FM only produced 1.4 nodes with TDZ. RP with KN produced 0 shoots and FM with KN produced 0.3 shoots.